Raul Ramirez appeals the 60-month sentence that the district court 1 imposed after he pleaded guilty to possessing a firearm during a drug-trafficking crime, in violation of 18 U.S.C. § 924(c)(1)(A)(i). Invoking Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), his counsel has moved to withdraw, filing a brief in which he raises a challenge to the sentence imposed.

Ramirez cannot challenge his sentence, however, because he specifically stipulated to it in his written plea agreement. See United States v. Nguyen, 46 F.3d 781, 783 (8th Cir. 1995) (defendant who explicitly and voluntarily exposes himself to specific sentence may not challenge that punishment on appeal). Further, having carefully reviewed the record in accordance with Penson v. Ohio, 488 U.S. 75, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we find no nonfrivolous issues.

Accordingly, we affirm the judgment. We also grant counsel’s motion to withdraw on condition that he show that he has informed Ramirez of the procedures for petitioning the Supreme Court for certiorari, in compliance with Part V of our plan to implement the Criminal Justice Act.